Fracture resistance of endocrowns made from different CAD/CAM materials after prolonged fatigue aging

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Abstract Objectives The aim of this study was to evaluate the fracture resistance of endocrowns made of experimental short fiber-reinforced CAD/CAM block (SFRC CAD) in comparison with different commercial CAD/CAM materials. Materials and methods In this study, 60 sound mandibular molar teeth with similar occlusal sizes (± 1 mm) were used. Standard preparations simulating an endocrown cavity were prepared and the teeth were divided into four groups randomly. After the digital photoimpression of the prepared cavities using a dental intraoral scanner (CEREC), the restorations were designed (4 mm high) and milled using IPS e.max, Cerasmart 270, Katana Avencia and SFRC CAD blocks (n = 15/per group). Restorations were cemented with self-adhesive dual-cure resin cement (G-Cem One). The specimens were immersed in a 37 °C water bath within the chewing simulator. Following cyclic fatigue aging for 1.000.000 cycles (Fmax=150 N), a quasi-static load was applied using a universal testing machine at a speed of 1 mm/min. Fractography analysis was conducted using optical microscopy. Results According to the data obtained, there are statistically significant differences in fracture resistance values between different CAD/CAM materials (p < 0.05). The highest values were observed in the experimental SFRC CAD group (3025 N), while the lowest values were observed in the IPS e.max group (2295 N). Conclusions The type of CAD/CAM restorative material influences the fracture resistance of endocrowns. SFRC CAD blocks could potentially serve as an alternative material for endocrown restorations in the future. Clinical relevance Endocrowns fabricated from SFRC CAD blocks have demonstrated promising fracture behavior, suggesting their suitability for clinical testing.